Ball core



Feb. 22, 1944. G K, RYN 2,342,603

` BALLl CORE Filed July 20, 1940 JEDE-imi.. 555-75575 ai? j MM@- Patented Feb. 22, 1944 BALL OGRE George K. Ryan, Akron, Ohio, assigner to The B.' F. Goodrich'Company, NewYork; N-Yma corporation of New York Application JulyY 20,` 1940, SerialfNo.v 346,6012

2'. Ciaims.

This invention relates to ball cores, especially cores for golf balls, although theinvention is useful in the manufacture' of cores for-baseballs and other types of balls where high resilience for long flight following impact is desired. The invention is directed more especially tol the construction of the core, upon which rubber thread or tape is subsequently wound under high tension.

It has been proposed heretofore to provide such cores by molding a shell'of'rubber upon a frozen pellet of a mixture of glue-glycerine or other substance to provide a liquid center, the shell being for the purpose of'providing a winding surface for the rubber thread andretaining the liquid.

Such constructions, however, have notv been fully satisfactory where it has been desired to increase the internal liquid pressurein the core of the completed ball' byneedle injection, there having been no adequate provision for preventing leakage through the needle opening after the injection. In attempts to provide a seal forthe needle it has been proposed to provide a vulcanized rubber shell having an inner layer of unvulcanized sealing compound, but so far as I am aware no satisfactory way of utilizing this construction has been available, especially with reference to the problem of providing' a liquid pellet accurately centered in such shell. It has been exceedingly difficult to obtain true concentricity'of a pellet within an'unvulcanized mass, and because of this it has been proposed to obtain the liquid center by needle injection of the squeezed'shell wth'the accompanying diinculty of avoiding adhesion of the unvulcanized rubber as a result of such squeezing and with the further difculty ofV providing a suitably spherical' core on which the winding of the rubber thread could be effectively carried out.

Chief among the objects of this invention are to provide a core construction and procedure rfor making the same,.avoid or obviatin'g the above discussed and other difficulties which have existed in prior procedures, to provide a core that has a satisfactory degree of softness or distortability so that the elasticity of the winding upon it may be fully availed of, together with a firm surface of the core such that the winding under high tension may be effected without cutting into such surface, to provide also for effectively sealing when the completed ball is needled for increasing the internal pressure by injection, and to eiTect such sealing without requiring any special taping of the core prior to winding the narrower elastic rubber thread. A further object is to provide these improved results by a procedure that is cont. I.. a

venient and suitable forrapid and economical manufacture.

These and other objects will be apparent from the following' description; reference beinghad to ther following drawing,- ir'rwhlch:

Fig. l is a verticalsectionthrough a half-mold mounted in a vulcanizingpress.`

Fig. 2 is a section taken`V along the line 2;--2v of Fig. 1.

Fig. 3 is a view ofy afrozenpellet ready forv incorporation in the core.

Fig. 4 is a vieW'like'Fig; l, showing the halfmold thereof associatedzwith another half-mold in a vulcanizingpress;

Fig. 5 is a View like Fig. 4 but showing two half'- molds of larger'cavity size used in a'subsequent step of the-procedure.

Fig. 6 is a view of a ball after the winding of rubber'thread has beenapplied.

Fig. 7 is a view ofthe completed ball, parts being-broken away to illustrate itsconstruction,

and a hollow needle beingfshown through the wall thereof for injection to subject the ball to high internal pressure.

As hereinbefore stated the invention-isochcerned primarily with' the construction of the core upon which the elastic'rubberthreadis to be Wound.' In accordance with'thisinvention I provide for. producing a. softcore; withits inher ent advantagesof makingypossible a ball capable of'v longflight as av result of the distortion of the core; and elastic winding underimpact, and there is made possible a construction that'. will seal' eiectively after theV injection' needle has been withdrawn. At the'same timethere isprovided thesomewhat anomalousproperties ofa rm suiu face ofr the core such that'winding'of the elasticv thread thereupon is facilitated; together with a core body that* maintains its spherical shapeoduring handling in the manufacturing operations, and a permanent location' of the parts thereof, concentrically -disposed,`without likelihoodiof `settling or otherwise shifting'or elementsv outv ofsoftening agent incorporated in it but preferably is fully vulcanized so as to maintain its shape and support the liquid center concentrically therein. While all the reasons for the successful sealing may not be fully apparent, the mineral oil or equivalent softening agent in the rubber of the shell II promotes the sealing ability apparently by Virtue of the self-sealing action that results from such agent, rendering the surface of the rubber in a needling hole tacky as compared to a surface of rubber without the softening agent, so that the material acts to heal or close the hole permanently in the ball through the tendency of the material to blend or cohere at the hole under the compression of the tensioned winding. At the same time the resistance to distortion of the rubber-like material under pressure is reduced by the softening agent so that effective pressure to close the opening is obtained. Thus, a self-healing action here is obtained despite the highly distortable but non-ilowable, vulcanized character of the material without the disadvantages hereinabove discussed accompanying such flow if the rubber were unvulcanized. The rm character of the cap I2 serves as a backing when the needle has been withdrawn after injection of the completed ball to resist outward flow of the center materials and to facilitate sealing by the soft rubber of the shell I I, and the cap I2 serves also by its rm property to facilitate winding of the rubber thread immediately upon the same under high tension without undesirable cutting of its surface and without requiring a primary application of rubber tape as distinguished from narrow thread.

In order to obtain true concentricity of the pellet Illa within the shell II, the latter preferably is formed as two half-shells and partially vulcanized in such form before the introduction of the pellet. Such formation of each half-shell Ila', is illustrated in Fig. l wherein a half-mold I3 with a cover I4 denes a suitable cavity therebetween for producing the half-shell Ila. During the molding, heat may be supplied from steam jacketed press platens I5, I6 so that the half-shell I la will be semi-vulcanized to hold its shape when removed from the mold.

Two half-shells Ila, IIa, partially vulcanized are combined with a central frozen pellet Illa and placed in a mold shown in Fig. 4, which mold comprises sections I3, Il. The mold may be held closed between heated platens I8, I9 of sufficient time for the halves of shell Il to become firmly united and for the composition thereof to become nearly vulcanized, while nevertheless retaining its soft character. The shell thus formed is then placed in a mold of larger cavity together with a surrounding body of rubber to mold thereon the cap I2. This may be effected as shown in Fig. 5 in associated mold halves 20, 2 I, and again heated platens 22, 23 may be used to supply heat to vulcanize the rubber compositions in such mold. The composition of the cap I2 is preferably of a type that cures with comparative rapidity, so that the shell II which has already had two stages of cure, will complete its vulcanization with the cap I2, and so that the core as it is taken from the mold of Fig. 5 is a fully vulcanized core which does not require delicate handling and which is immediately ready for the operation of winding the rubber thread thereon.

Such rubber thread, indicated at 24, may be wound upon the core in any suitable manner, after which a cover 25 of gutta percha or the like may be molded directly upon the winding 24. The ball is then ready for the introduction of a hollow needle 26 as shown in Fig. 7 to inject added liquid into the center under high pressure. Upon removal of the needle 2B, the rubber of the shell II, while fully vulcanized and therefore lacking flowability in the sense of unvulcanized rubber, by coaction with the cap I2 of relatively firm rubber and the pressure of the superimposed winding, is nevertheless effective to seal the needle opening and prevent the liquid of the center from following the needle and leaking out from the core.

While the invention has been described with reference to the method of Ymaking golf balls, features thereof have been found useful also in the manufacture of other balls, such for example as baseballs Where yarn rather than rubber thread is wound upon the core or center, but under tension thereon.

Variations may be made without departing from the scope of the invention as it is defined in the following claims.

I claim:

1. A golf ball core suitable for high tension winding thereon and needle injection of the completed ball, said core comprising a distortable center, a shell enclosing the center comprising non-howable, self-healing material resulting from vulcanization of a mixture of rubber and a softening agent incorporated therein, and a cap thereon of a relatively firm vulcanized rubber material,

the non-flowing vulcanized shell and cap promoting maintenance of concentricity under the high tension winding, and the self-healing character of said shell providing self-sealing of the hole from the injection needle.

2. A golf ball core suitable for high tension winding thereon and needle injection of the completed ball, said core comprising a distortable center, a shell enclosing the center comprising non-flowable, self-healing material resulting from vulcanization of a mixture of rubber and mineral oil incorporated therein, and a cap thereon of relatively firm vulcanized rubber material, the non-flowing vulcanized shell and cap promoting maintenance of concentricity under the high tension winding, and the self-healing character of said shell providing self-sealing of the hole from the injection needle.

GEORGE K. RYAN. 

